Seismograph and needle: what they have in common

1. Step 1. Seismograph — has part — Pendulum. An inertial mass.
2. Step 2. Pendulum — uses — Newton’s laws. The swing is described by Newtonian mechanics.
3. Step 3. Newton’s laws — is used in — Billiards. Collisions of balls.
4. Step 4. Billiards — is made of — Wool. The baize.
5. Step 5. Wool — is material for — Trousers. The oldest trousers (Yanghai) were sewn from wool.
6. Step 6. Trousers — uses — Needle. Trousers were sewn with a needle.

Open Evothings